Currently, there is much development work being undertaken in the utilization of SIRs, sometimes referred to as air bags, to protect vehicle occupants during side collisions. One of the important factors in maximizing occupant protection is having the correct relationship between the position of the occupant and the air bag upon inflation.
Experimentally, air bags have been placed in vehicle doors. However, when utilized for side impact, due to the fore and aft adjustment of the vehicle seat, the exact position of the vehicle occupant with respect to the air bag is a variable. To minimize the aforementioned variable, the utilization of SIRs which are actually mounted to the vehicle seat have been proposed, thereby keeping constant the positional relationship of the air bag to the seat occupant.